CompTIA Network+ Practice Questions: Networking Concepts

66 free, exam-style CompTIA Network+ (N10-009) practice questions covering Networking Concepts. Each question shows the correct answer and a clear explanation. Ready for the real thing? Take the full timed quiz below.

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Q1. Which protocol operates at layer 4 of the OSI model and provides connection-oriented communication?

Explanation: TCP (Transmission Control Protocol) operates at layer 4 and ensures reliable, connection-oriented data delivery. Learn more.

Q2. What is the purpose of a subnet mask?

Explanation: Subnet masks distinguish between network and host portions of an IP address. Learn more.

Q3. Which protocol resolves IP addresses to MAC addresses?

Explanation: ARP (Address Resolution Protocol) maps IP addresses to physical MAC addresses. Learn more.

Q4. Which device operates at Layer 3 of the OSI model?

Explanation: Routers operate at Layer 3 (Network layer) to route packets between networks. Learn more.

Q5. Which IPv6 address type is equivalent to IPv4's 169.254.0.0/16?

Explanation: IPv6 link-local addresses (fe80::/10) are self-assigned like IPv4 APIPA addresses. Learn more.

Q6. Which network topology provides redundant paths between nodes?

Explanation: Mesh topologies provide multiple paths for fault tolerance. Learn more.

Q7. What does a /28 subnet mask provide?

Explanation: /28 (255.255.255.240) provides 16 total addresses minus 2 (network/broadcast) = 14 usable. Learn more.

Q8. Which IPv6 address notation correctly compresses leading zeros?

Explanation: Leading zeros can be removed, and a single :: can replace consecutive zeros. Learn more.

Q9. What is the purpose of an SLAAC (Stateless Address Autoconfiguration)?

Explanation: SLAAC allows IPv6 hosts to self-configure addresses using router advertisements. Learn more.

Q10. Which network device operates at Layer 2 but can filter based on Layer 3/4 information?

Explanation: Multilayer switches combine Layer 2 switching with Layer 3 routing capabilities. Learn more.

Q11. Which IPv6 address type is used for a single interface on multiple hosts?

Explanation: Anycast addresses deliver packets to the nearest of multiple receivers. Learn more.

Q12. What is the purpose of the ARP table?

Explanation: The ARP (Address Resolution Protocol) table stores mappings between IP addresses and MAC addresses on a local network, enabling devices to communicate over Ethernet. Learn more.

Q13. Which protocol is used for automatic IPv6 address configuration?

Explanation: IPv6 supports both stateful (DHCPv6) and stateless (SLAAC) configuration. Learn more.

Q14. What is the purpose of a default gateway?

Explanation: A default gateway serves as the access point or IP router a computer uses to send information to another network. Without it, systems wouldn’t know how to reach destinations outside the local subnet, such as websites on the internet. Learn more.

Q15. What is the purpose of a network switch?

Explanation: A network switch connects devices within a LAN and forwards data based on MAC addresses. Learn more.

Q16. Which protocol operates at layer 4 of the OSI model and provides connection-oriented communication?

Explanation: TCP (Transmission Control Protocol) ensures reliable, ordered delivery of data between applications over networks. It establishes connections using a handshake process and operates at Layer 4 (Transport Layer) of the OSI model. Learn more.

Q17. What is the purpose of a subnet mask?

Explanation: A subnet mask divides an IP address into the network and host portions. It determines which part of the address represents the network and which part represents individual devices (hosts), enabling routing and IP management. Learn more.

Q18. Which cable type is immune to electromagnetic interference (EMI)?

Explanation: Fiber optic cables transmit data as light through glass or plastic fibers, making them completely immune to electromagnetic interference (EMI) and ideal for high-speed, long-distance communication. Learn more.

Q19. Which port does SSH use by default?

Explanation: SSH (Secure Shell) uses TCP port 22 to provide encrypted remote access to devices and servers. It is commonly used for administrative access to Linux systems and secure file transfers via SCP or SFTP. Learn more.

Q20. What is the maximum speed of 1000BASE-T Ethernet?

Explanation: 1000BASE-T supports data transmission speeds up to 1 Gigabit per second over standard Cat 5e or Cat 6 twisted-pair copper cabling, making it a common choice in modern LAN environments. Learn more.

Q21. Which protocol resolves IP addresses to MAC addresses?

Explanation: ARP (Address Resolution Protocol) maps IP addresses to MAC addresses, enabling devices to communicate on a local network. It operates at Layer 2 and is essential for packet delivery in Ethernet environments. Learn more.

Q22. What is the purpose of an MX record in DNS?

Explanation: MX (Mail Exchange) records direct email to the correct mail servers. Learn more.

Q23. Which network topology provides the highest fault tolerance?

Explanation: Mesh networks offer redundant paths between nodes, ensuring continued operation if one link fails. Learn more.

Q24. What is the primary purpose of jumbo frames?

Explanation: Jumbo frames (MTU >1500 bytes) improve throughput by reducing header overhead. Learn more.

Q25. Which IPv6 address type is used for a single interface on multiple hosts?

Explanation: Anycast addresses deliver packets to the nearest of multiple identical interfaces. Learn more.

Q26. Which DNS record type provides reverse lookups?

Explanation: PTR (Pointer) records map IP addresses to hostnames for reverse DNS queries. Learn more.

Q27. Which cloud model provides shared hardware resources between organizations?

Explanation: Community clouds serve multiple organizations with shared compliance requirements. Learn more.

Q28. Which of the following IP addresses is a private, non-routable IP address according to RFC 1918?

Explanation: The 192.168.0.0/16 block is designated for private use. 172.32.x.x is public (private is 172.16.0.0 - 172.31.255.255). 11.x.x.x is public. 169.254.x.x is APIPA. Learn more.

Q29. Which IPv6 feature allows a device to automatically configure its own link-local address without a DHCP server?

Explanation: While SLAAC uses NDP for address configuration, the Neighbor Discovery Protocol (NDP) itself includes the mechanisms (like Router Solicitation/Advertisement) that enable devices to discover routers and auto-configure addresses, including link-local addresses (fe80::/10 prefix + modified MAC). Learn more.

Q30. Which of the following is a characteristic of single-mode fiber optic cable compared to multi-mode fiber?

Explanation: Single-mode fiber has a much smaller core diameter and uses laser light sources, allowing it to transmit signals over significantly longer distances with less signal degradation (attenuation) compared to multi-mode fiber. Learn more.

Q31. Which of the following protocols is connectionless and operates at the Transport layer of the OSI model?

Explanation: UDP (User Datagram Protocol) is a connectionless protocol that operates at Layer 4 (Transport). It provides fast, low-overhead data delivery but does not guarantee reliability or order of packets, making it suitable for applications like DNS, DHCP, and streaming. Learn more.

Q32. Which of the following describes a MAN (Metropolitan Area Network)?

Explanation: A MAN typically covers a larger geographic area than a LAN (Local Area Network) but smaller than a WAN (Wide Area Network), often interconnecting multiple LANs within a city or metropolitan region. Learn more.

Q33. What is the primary function of NAT (Network Address Translation)?

Explanation: NAT allows multiple devices on a private network using private IP addresses (RFC 1918) to share a single public IP address for internet access. This conserves public IP addresses and provides a degree of security by hiding internal network structures. Learn more.

Q34. Which of the following is a characteristic of CSMA/CD used in older Ethernet networks?

Explanation: CSMA/CD (Carrier Sense Multiple Access with Collision Detection) is an access method where devices listen to the network medium. If it's clear, they transmit. If a collision occurs (two devices transmit simultaneously), they stop, wait a random time, and try again. It was used in half-duplex Ethernet hubs. Learn more.

Q35. What is the well-known TCP port number for HTTP?

Explanation: HTTP (Hypertext Transfer Protocol), used for web browsing, uses TCP port 80 by default. HTTPS (secure HTTP) uses TCP port 443. Learn more.

Q36. Which of the following is a cloud deployment model where the infrastructure is provisioned for exclusive use by a single organization comprising multiple consumers (e.g., business units)?

Explanation: A private cloud is operated solely for a single organization. It can be managed by the organization or a third party and may exist on-premises or off-premises. It offers greater control and security. Learn more.

Q37. Which layer of the OSI model is responsible for logical addressing and path determination (routing)?

Explanation: Layer 3, the Network layer, is responsible for providing logical addressing (e.g., IP addresses) and determining the best path for data packets to travel from a source to a destination across one or more networks (routing). Learn more.

Q38. At which layer of the OSI model is data encryption and compression primarily handled to ensure application data is presented in a usable format?

Explanation: The Presentation Layer (Layer 6) is responsible for data formatting, including character encoding, compression, and encryption/decryption, ensuring that data sent by the application layer of one system can be understood by the application layer of another system. Learn more.

Q39. What is the primary advantage of using Classless Inter-Domain Routing (CIDR) notation (e.g., 192.168.1.0/24) for IP addressing?

Explanation: CIDR allows network administrators to define subnets of variable sizes, leading to more efficient use of IP address space. It also enables route summarization (aggregation) to reduce the size of routing tables. Learn more.

Q40. What is the scope of an IPv6 unique local address (ULA) (FC00::/7)?

Explanation: Unique Local Addresses (ULAs) are analogous to IPv4 private addresses. They are intended for local communications within a site or between a limited number of sites and are not meant to be routed on the global internet. Learn more.

Q41. At which layer of the OSI model do MAC addresses and network switches primarily operate?

Explanation: The Data Link layer (Layer 2) is responsible for physical addressing using MAC addresses, framing data for transmission, and error detection. Network switches operate at this layer to forward frames based on destination MAC addresses within a local network segment. Learn more.

Q42. Which layer of the TCP/IP model is responsible for IP addressing, routing of packets between different networks, and path determination?

Explanation: The Internet Layer in the TCP/IP model (which corresponds to the Network Layer in the OSI model) is responsible for logical addressing (IP addresses), routing packets across different networks using protocols like IP, and determining the best path for data to travel. Learn more.

Q43. Which type of IPv4 address is used to send a packet from a single source to multiple, specifically selected destinations that are part of a defined group?

Explanation: Multicast addressing allows a source to efficiently send a single packet that is delivered to a group of interested receivers (the multicast group). IPv4 multicast addresses are in the Class D range (224.0.0.0 to 239.255.255.255). This is used for applications like IPTV and online gaming. Learn more.

Q44. What does "full-duplex" communication mean in the context of a modern switched Ethernet link?

Explanation: Full-duplex communication allows a network device to send and receive data at the same time on a single network link. This is possible on switched Ethernet links (not hubs) because there are separate transmit and receive paths, eliminating the possibility of collisions on that segment. Learn more.

Q45. What is the standard IPv6 loopback address, used by a host to send packets to itself for testing the TCP/IP stack?

Explanation: The IPv6 loopback address is `::1` (which is the compressed form of `0:0:0:0:0:0:0:1`). It serves the same purpose as the 127.0.0.1 address in IPv4, allowing a host to send network packets to itself for diagnostic and testing purposes. Learn more.

Q46. What is the fundamental difference between network bandwidth and network throughput?

Explanation: Bandwidth refers to the maximum data carrying capacity of a network link, often stated by the technology standard (e.g., a 1 Gbps Ethernet link has a bandwidth of 1 Gbps). Throughput, on the other hand, is the actual rate at which data is successfully transferred over the link, which is often lower than the bandwidth due to factors like network overhead, latency, congestion, packet loss, and protocol inefficiencies. Learn more.

Q47. Which port number is associated with the SMB (Server Message Block) protocol used for file sharing in Windows environments?

Explanation: SMB directly over TCP/IP uses port 445. Older versions used NetBIOS ports (137-139), but modern implementations rely on 445. Learn more.

Q48. Which IPv6 address type is intended for one-to-nearest delivery among multiple nodes sharing the same address?

Explanation: IPv6 anycast addresses are assigned to multiple interfaces, and routing delivers traffic to the nearest one. Learn more.

Q49. Which WAN technology uses software-defined control to choose paths across multiple links?

Explanation: SD-WAN centrally manages WAN traffic policies and can select paths across broadband, LTE, MPLS, or other links. Learn more.

Q50. Which cable type is immune to electromagnetic interference?

Explanation: Fiber optic cable uses light rather than electrical signals, making it immune to EMI. Learn more.

Q51. Which cloud connectivity model provides private dedicated connectivity to a provider?

Explanation: Cloud providers offer dedicated private connectivity services for lower latency, predictable performance, and private routing. Learn more.

Q52. Which IPv6 multicast address is used for all nodes on the local link?

Explanation: ff02::1 is the IPv6 all-nodes link-local multicast address. Learn more.

Q53. Which topology connects each site to a central site instead of directly to every other site?

Explanation: Hub-and-spoke designs centralize connectivity through a hub site. Learn more.

Q54. Which technology extends a Layer 2 segment over a Layer 3 network using encapsulation?

Explanation: VXLAN encapsulates Layer 2 frames in UDP to extend network segments across Layer 3 infrastructure. Learn more.

Q55. Which port is used by NTP by default?

Explanation: Network Time Protocol commonly uses UDP port 123. Learn more.

Q56. A network uses 10.0.0.0/8 internally. What address type is this?

Explanation: 10.0.0.0/8 is an RFC 1918 private IPv4 address range. Learn more.

Q57. Which IPv6 address type is used for one-to-one communication and is routable on the internet?

Explanation: A global unicast address is the IPv6 equivalent of a public IPv4 address, routable across the internet and used for one-to-one communication between hosts. Learn more.

Q58. Which network topology connects every device to a central device, such as a switch, making it the most common topology in modern LANs?

Explanation: A star topology connects all devices to a central point, typically a switch, providing easier troubleshooting and better fault isolation than bus or ring topologies. Learn more.

Q59. What does a subnet mask of 255.255.255.192 provide in terms of usable hosts per subnet?

Explanation: A /26 subnet mask (255.255.255.192) leaves 6 host bits, providing 2^6 - 2 = 62 usable host addresses per subnet after subtracting the network and broadcast addresses. Learn more.

Q60. Which type of connector is commonly used with single-mode fiber optic cable for long-distance, high-precision alignment?

Explanation: LC and SC connectors are widely used with single-mode fiber, offering precise alignment needed for the narrow core diameter of single-mode fiber used in long-haul, high-bandwidth links. Learn more.

Q61. Which cloud deployment model combines both private and public cloud resources, allowing data and applications to be shared between them?

Explanation: A hybrid cloud combines private and public cloud infrastructure, allowing organizations to keep sensitive workloads on-premises while leveraging public cloud scalability for other needs. Learn more.

Q62. How many usable host addresses are available in a conventional IPv4 /27 subnet?

Explanation: A /27 leaves five host bits, producing 32 total addresses. Subtracting the network and broadcast addresses leaves 30 usable host addresses. Learn more.

Q63. A router has matching routes for 10.20.0.0/16 and 10.20.30.0/24. Which route is selected for 10.20.30.55?

Explanation: Routers use longest-prefix matching. The /24 route is more specific than the /16 route and is therefore selected. Learn more.

Q64. Which Ethernet technique adds a provider VLAN tag around a customer's existing VLAN tag?

Explanation: QinQ encapsulates a customer 802.1Q tag inside a service-provider VLAN tag, allowing multiple customers' VLANs to cross a provider network. Learn more.

Q65. A router must send voice traffic over a low-latency circuit while other traffic follows the normal routing table. Which feature should be configured?

Explanation: Policy-based routing can select a next hop using criteria such as source, protocol, or application instead of relying only on the destination route. Learn more.

Q66. What is the main operational benefit of infrastructure as code for network deployments?

Explanation: Infrastructure as code makes configurations repeatable, reviewable, and version-controlled, reducing manual drift and deployment errors. Learn more.

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